1. Field of the Invention
The present invention relates to an improved homokinetic joint for use with a drive shaft of an automobile.
As one type of homokinetic joints for use with propeller shafts and drive shafts, there are known ball type cross-groove joints (VL). Such joints are used e.g. as sliding type homokinetic joint mounted inboard for front wheels and inboard and/or outboard for the rear wheels of a car.
2. Description of the Prior Art
As one example of such a homokinetic joint, we show in FIG. 14 a joint having a closed-end type mounting portion. It comprises an inner ring 1, a cage 2, balls 3 and an outer ring 4. When mounting this homokinetic joint on a shaft 5, the end of the shaft 5 is fixed to the inner ring 1 by means of a retaining ring 6 and a boot adaptor 7 and a boot 8 are fitted on the outer periphery of the shaft 5. The boot adaptor 7 is secured by caulking to the outer periphery of the outer ring 4 at its open end. Numeral 9 indicates a seal member such as an O-ring.
The boot adaptor 7 is provided to prevent the balls 3 from dropping out of ball grooves formed in the outer ring 4 and the inner ring 1 even if the angle .theta. becomes excessively large as shown in FIG. 15. FIG. 16 shows the relation between the angle .theta. and the sliding movement of the shaft. Letter A indicates the line of interference between the inner ring and the cage. B indicates the line where the balls drop out. E is the line of interference between the balls and the adaptor. F shows the line of interference between the adaptor and the shaft.
Such a conventional boot adaptor has a complicated shape and has to be manufactured with high dimensional accuracy. Further, it has to be subjected to an anti-corrosion surface treatment or made of an anti-corrosive material. Such a boot adaptor is thus very costly. Moreover, special facility is needed to caulk it to secure it to the outer ring. Such coupling work involves many steps. A seal member such as an O-ring is also needed to prevent leakage of grease. This also adds to the cost.
Such a boot adaptor is formed by pressing a steel plate and serves as a stopper by interfering with the shaft. It is so designed that the shaft will not form a larger angle than a predetermined one with respect to the outer ring while in use. But if it should operate at an excessive angle and interfere with a strong force, the boot adaptor would be deformed. This may cause insufficient coupling between the boot and the boot adaptor, thus hampering the seal therebetween.